Don't "push checkboxes" on radio buttons

Radio buttons were being created like:

```html
<div class="controls">
	<label for="status" class="radio inline">
		<input type="hidden" name="status" value="" id="status">
		<input required="true" value="draft" checked="1" id="status" type="radio" name="status">Draft</label>
	<label for="status2" class="radio inline">
		<input type="hidden" name="status" value="" id="status">
		<input required="true" value="pending" id="status2" type="radio" name="status">Pending</label>
	<label for="status3" class="radio inline">
		<input type="hidden" name="status" value="" id="status">
		<input required="true" value="published" id="status3" checked="checked" type="radio" name="status">Published</label>
</div>
```

I think that push_checkboxes was only meant to be for checkboxes, which this request enforces.